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Can you change the shard key in MongoDB?
Starting in MongoDB 5.0, you can reshard a collection by changing a collection’s shard key. Starting in MongoDB 4.4, you can refine a shard key by adding a suffix field or fields to the existing shard key. In MongoDB 4.2 and earlier, the choice of shard key cannot be changed after sharding.
How do you Shard a collection in MongoDB?
To shard a collection on a compound hashed index, specify the full namespace of the collection and the target compound hashed index to use as the shard key: Starting in MongoDB 4.4, you can refine a collection’s shard key by adding a suffix field or fields to the existing key.
How does hashed sharding work in MongoDB 4.4?
Sharding on a Compound Hashed Index MongoDB 4.4 adds support for creating compound indexes with a single hashed field. To create a compound hashed index, specify hashed as the value of any single index key when creating the index.
Which is an example of a hashed shard key?
Hashed keys are ideal for shard keys with fields that change monotonically like ObjectId values or timestamps. A good example of this is the default _id field, assuming it only contains ObjectId values. To shard a collection using a hashed shard key, see Shard a Collection. Hashed vs Ranged Sharding ¶
Which is the sharding strategy used in MongoDB?
Sharding Strategy¶ MongoDB supports two sharding strategies for distributing data across sharded clusters. Hashed Sharding¶ Hashed Sharding involves computing a hash of the shard key field’s value. Each chunk is then assigned a range based on the hashed shard key values.
Can a client connect to more than one shard in Mongo?
Clients should never connect to a single shard in order to perform read or write operations. You can connect to a mongos the same way you connect to a mongod, such as via the mongo shell or a MongoDB driver. MongoDB supports two sharding strategies for distributing data across sharded clusters.
When to create a supporting Index in MongoDB?
When sharding an empty collection, MongoDB creates the supporting index if the collection does not already have an appropriate index for the specified shard key. See Shard Key Indexes.